There are three distinct performance measures used to categorize roadside crash cushions, including redirective/non-redirective, gating/non-gating, and restorable/sacrificial energy absorbers. The first category refers to the capability of the crash cushion to contain and redirect oblique impacts into the rear of the cushion while the second category refers to the capability of the vehicle to break through the system during end-on impacts and travel behind the cushion and any barrier to which it is attached.
The third category refers to whether or not the crash cushion can be restored and reused after an impact without replacement of energy-dissipative components. A major consideration in relation to the third category is cost, specifically the cost for repairing the system after an impact. Sacrificial crash cushions utilize energy-absorbing elements that must be replaced after every impact. Restorable crash cushions utilize reusable components and, after most impacts, merely need to be pulled back into position. Because the costs for reusable crash cushions are much greater than those for cushions with replaceable energy absorbers, the most widely used crash cushions fall into the sacrificial category. It is estimated that more than 3,500 sacrificial crash cushions are sold in this country every year at a total cost in excess of $35 million.
Because the expenses associated with replacing energy absorbers can be high, it is desirable to use restorable crash cushions. It would be desirable to have restorable crash cushions that are relatively inexpensive to install, maintain, and restore.